Which of the following is best described as an

Question

acid-base reaction?
1. NaCl + AgNO3 !NaNO3 + AgCl
2. NH3 + H2O ! NH+
4 + OH−
3. 2HgO ! 2 Hg + O2
4. Ca + 2H2O ! Ca(OH)2 + H2
5. KCl + NH4NO3 ! KNO3 + NH4Cl

Answer 1

#2 for sure.